The present invention relates to a method of manufacturing a hollow shaft having a flange at one end thereof.
A hollow shaft to which the present invention relates is often used as an output shaft in a planetary gearing device of a speed change gear box in a motor vehicle. Such kind of hollow shaft is usually manufactured by engaging a flange member with a hollow shaft member through plastic working treatment by virtue of caulking combination.
Japanese Unexamined Patent Publication No. 58-100926 has disclosed a shaft manufacturing method in which a ring-like member is integrally formed at one end of a hollow shaft through plastic working treatment. In detail, an end portion of a cylindrical work piece engaged with a ring-like member is bent backwardly, so that the cylindrical work piece and the ring-like member may be firmly fixed together by virtue of caulking combination.
Further, Japanese Unexamined Patent Publication No. 10-156450 has disclosed another shaft manufacturing method in which a ring-like member is engaged at one end of a hollow work piece, an outer periphery portion of the hollow work piece protruding beyond the ring-like member is bent towards the ring-like member, so that the ring-like member and the hollow work piece may be firmly fixed together by virtue of caulking combination.
However, each of the above manufacturing methods requires that part of a hollow work piece protruding beyond a ring-like member (engaged with the hollow work piece) is subjected to a plastic working treatment so that the ring-like member may be pressed in the axial direction so as to be fixed in the hollow work piece. Although each of these methods is proved to be effective in securing a ring-like member (having a predetermined thickness in its axial direction) on to a hollow shaft with a predetermined strength, none of them has been provided to be effective in firmly securing a plate-like member onto a hollow shaft by virtue of caulking combination.
The present invention has been accomplished in view of the above problem, its object is to provide a method in which a plate-like flange member may be firmly secured at the front end of a hollow shaft member through a plastic working treatment by virtue of caulking combination, so as to manufacture a hollow shaft having a flange at one end thereof.
According to the present invention, there is provided a method of manufacturing a hollow shaft having a flange at one end thereof, said method comprising the steps of: preparing a plate-like flange member having an axial project ion including a constricted portion on one side thereof; preparing a hollow shaft member having an elongate internal space arranged in the axial direction thereof; engaging the axial projection of the plate-like flange member into a front end portion of the hollow shaft member and at the same time inserting a mandrel into the hollow shaft member; pressing the hollow shaft member in its axial direction towards the plate-like flange member while performing a shear spinning treatment on the outer periphery surface of the hollow shaft member so as to reduce the size of the hollow shaft member in its radial direction; engaging the front portion of the hollow shaft member with the constricted portion of the axial projection of the plate-like flange member by virtue of caulking combination.
In one aspect of the present invention, a front end portion of the axial projection of the plate-like flange member has a turning-prevent ion structure such as a serration structure formed on its outer periphery surface.
In another aspect of the present invention, the plate-like flange member and the hollow shaft member, which are to be engaged with each other by virtue of caulking combination, are made of a material containing 0.2-0.6 wt % of C, 0.01-0.1 wt % of Si, 0.05-0.5 wt % of Mn, 0.001-0.01 wt % of B, 0.01-0.1 wt % of Ti or Nb, with the balance being Fe, and are subjected to a heating treatment upon being combined into an integral body.
With the use of the present invention, when the axial projection of the plate-like flange member is engaged into the front portion of the hollow shaft member by virtue of caulking combination, the front portion of the hollow shaft member may be partially combined into the constricted portion of the axial projection, thereby effecting an extremely strong caulking combination of the plate-like shaft member with the hollow shaft member.
Further, if a front end portion of the axial projection of the plate-like flange member has a turning-prevention structure such as a serration structure formed on its outer periphery surface, it is sure to obtain a further strong combination of the two members.
Moreover, since the plate-like flange member and the hollow shaft member are made of a material containing only a reduced amount of Si and Mn, it is allowed to ensure an improved ductility even if they contain a relatively large amount of C, thereby allowing a desired plastic working treatment on these members without causing any cracks.